JP2654166B2 - Electronically controlled cooker - Google Patents

Description

The present invention relates to an electronically controlled cooker such as a microwave oven that performs heating control based on humidity at the time of heating.

(B) Conventional technology Japanese Patent Application No. 62-167296 discloses a microwave oven that performs heating control based on humidity detected by a humidity sensor during heating. Specifically, the heating is controlled based on the difference between the first and second detected humidity when the first and second fixed times have elapsed from the start of heating.

Some microwave ovens have a turntable that rotates food.In this case, since the food moves sequentially in the heating chamber, the flow direction of the water vapor from the food to the humidity sensor changes sequentially. When the humidity is detected in accordance with the above, the detected humidity also changes sequentially.

Then, if the flow directions of the water vapor at the time of the first and second fixed times have changed and are different from each other, the difference between the first and second detected humidity detected at the time of the first and second fixed time has passed. However, the influence of the flow direction of the steam appears as an error, and accurate heating control cannot be performed.

In particular, if the food is wrapped, the water vapor from the food flows only through the breaks in the wrap. It is no longer possible to perform a proper heating control.

(C) Problems to be Solved by the Invention The present invention relates to a configuration in which heating is controlled based on a difference between first and second detected humidity when first and second fixed times have elapsed from the start of heating. This makes it possible to perform accurate heating control without causing the influence to appear in the difference even if the direction of steam flow from the food changes sequentially due to the rotation of.

(D) Means for Solving the Problems The electronically controlled cooker according to the present invention is provided with a heating chamber for storing food covered with wrap, a heating source for heating the food in the heating chamber, and a heating chamber. A turntable on which the food is placed, and a motor that rotates the turntable,
An exhaust port provided in the heating chamber and exhausting air in the heating chamber through an exhaust duct, a humidity sensor for detecting humidity when the food is heated by the heating source disposed in the exhaust duct, and from the start of heating. A first timer for measuring a first fixed time; a first humidity detector for detecting a first detected humidity of the humidity sensor when the first fixed time has elapsed by the first timer; A second timer for measuring a time longer than a predetermined time and for measuring a second predetermined time in which a difference from the first predetermined time is a natural number times the rotation period of the turntable; and a second timer. A second humidity detecting section for detecting a second detected humidity of the humidity sensor when a second fixed time has passed, a first detected humidity of the first humidity detecting section, and a second
And a control unit for controlling the heating source based on a difference between the second detection humidity and the humidity detection detection unit.

(E) Function The turntable is rotated a natural number of times from when the first fixed time elapses to when the second fixed time elapses.
The rotation position of the turntable is the same and the moving position of the food is the same both when the second fixed time elapses, and the flow direction of the water vapor from the food is the same when the two times elapse. Regarding the first and second detected humidities detected after the lapse of a certain time, the difference does not have an influence by the flow direction of the water vapor, and accurate heating control based on the difference between the detected humidities is performed.

(F) Embodiment FIGS. 1 and 2 show the structure of a microwave oven according to an embodiment of the present invention, in which a heating chamber (3) for storing food (2) is arranged in a microwave oven body (1). In addition, a door (4) for opening and closing a front opening of the heating chamber (3) and a keyboard (5) are arranged on a front surface of the main body (1). Such a keyboard (5) has a humidity key (6) for selecting humidity controlled heating, a start key (7), and the like. The heating chamber (3) is supplied with microwaves for heating the food (2) from a magnetron (8) serving as a heating source, and with ventilation air generated by a fan (9). When such ventilation air is supplied into the heating chamber (3), it is exhausted to the outside through the exhaust duct (10) with the atmosphere in the heating chamber (3) containing water vapor from the food (2). .
In the exhaust duct (10), a humidity sensor (1) for detecting the humidity of the atmosphere passing therethrough, that is, the humidity in the heating chamber (3).
1) is provided. A turntable (12) for rotating the food (2) is provided in the heating chamber (3). Such a turntable (12) is driven by a synchronous motor (13).

FIG. 3 shows a circuit of the microwave oven, and the control of the microwave oven is performed by a microcomputer (14) as a control unit. That is, such a microcomputer (14)
Key operation information from the keyboard (5) and humidity information from a sensor circuit (15) including the humidity sensor (11) are input, and a magnetron driving circuit (16) including the magnetron (8) is input based on the information. , A drive table (17) including the synchronous motor (13) and a fan drive circuit (18) including the fan (9).

FIG. 4 shows a flowchart of a control program of the microcomputer (14), and FIG. 5 shows a temporal change state of the output (detected humidity) of the humidity sensor (11). The operation of the microwave oven will be described in detail with reference to FIG.

The wrapped food (2) (there is a gap where water vapor leaks between the wrap and the food) is placed on the turntable (12) in the heating chamber (3), and the humidity control heating is performed. In order to operate the humidity key (6) with the keyboard (5), the magnetron drive circuit (16),
The drive of the turntable drive circuit (17) and the fan drive circuit (18) is started, microwave heating and rotation of the turntable (12) are started, and ventilation air is supplied into the heating chamber (3). When such ventilation air is supplied into the heating chamber (3), it is discharged to the outside through the exhaust duct (10) with the atmosphere in the heating chamber (3). In the subsequent S2 step, the heating elapsed time is started to be counted by the counter CNT in the microcomputer (14). In the next at S3 step waiting for斯Ru counting time to reach the first predetermined time T ₁ i.e. 30 seconds. This S3 step corresponds to a first clock section. And
When the first fixed time T ₁ (30 seconds) elapses from the start of heating, S4
In the step, the first detected humidity H1 detected by the humidity sensor (11) at this time is calculated by the microcomputer (14).
In the first register R1. This step S4 corresponds to a first humidity detecting section. Further waits for time measured by the counter CNT reaches the second predetermined time T ₂ i.e. 30 seconds in S5 step. This S5 step corresponds to a second clock section. When the second fixed time T ₂ (50 seconds) has elapsed from the start of heating, in step S6, the humidity sensor (11)
Is stored in the second register R2 in the microcomputer (14). This step S6 corresponds to a second humidity detecting section. In the following S7 step, the difference ΔH between the first and second detected humidities H1 and H2 (= H2−H1).
Is calculated, and in the next step S8, it is determined whether or not the difference ΔH is equal to or larger than a predetermined value Ha. Heating is controlled based on such a determination.

Here, the rotation cycle of the turntable (12) is 10 seconds at a power frequency of 60 Hz, and the difference between the first and second fixed times T ₁ and T ₂ is 20 seconds (= 50 seconds−20 seconds). ) And the difference
Twenty seconds is a natural number times, that is, twice as long as the rotation cycle of the turntable (12).

Accordingly, as the food (2) is rotated by the turntable (12), the flow direction of water vapor from the food changes successively, and the detected humidity changes sequentially as shown in FIG.
Since the rotation position of the turntable (12) is the same and the movement position of the food (2) is the same both at the time when the first and the first fixed times T ₁ and T ₂ have elapsed, the time at the time when both elapse has elapsed. The flow direction of steam from food (2) is the same,
The difference ΔH between the first and second detected humidities H1 and H2 is not affected by the flow direction of the steam. Therefore, the difference Δ
The determination as to whether or not H is equal to or greater than the predetermined value Ha (Step S8) is made accurately, and accurate heating control is performed.

(G) Effect of the Invention According to the present invention, in a configuration in which heating is controlled based on the difference between the first and second detected humidity at the time when the first and second fixed times have elapsed from the start of heating, the food is rotated by the turntable. Even if the flow direction of the steam from the food changes successively, this effect does not appear in the above difference, and therefore, a practical cooker that can perform accurate heating control can be provided.

[Brief description of the drawings]

1 is a front view, FIG. 2 is a sectional view, FIG. 3 is a circuit diagram, FIG. 4 is a flowchart of a microcomputer control program, and FIG. 5 is humidity. FIG. 6 is a diagram illustrating a temporal change state of a sensor output. (11) Humidity sensor, (12) Turntable,
(14) ... Microcomputer.

Claims (1)

(57) [Claims] 1. A heating chamber for storing food covered with wrap,
A heating source for heating the food in the heating chamber, a turntable disposed in the heating chamber for placing the food thereon, a motor for rotating the turntable, and exhausting air in the heating chamber provided in the heating chamber. An exhaust port that exhausts through a duct, a humidity sensor that detects humidity when the food is heated by the heating source disposed in the exhaust duct, and a first timer that counts a first fixed time from the start of heating, A first humidity detecting section for detecting a first detected humidity of the humidity sensor when a first fixed time has elapsed, a first time measuring section for measuring a time longer than the first fixed time from the start of heating; A second timer for measuring a second constant time in which the difference from the time is a natural number times the rotation period of the turntable; and a second timer for measuring the second constant time in the second timer. 2 Detects humidity A second humidity detecting section that, a control unit for controlling the heat source based on the difference between the first sensing humidity and the second sensing humidity of the second humidity detecting portion of the first humidity detection unit,
An electronically controlled cooker comprising: